Chapter 22 - Chapter 22 1 Discuss the production of sex...

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Chapter 22 1. Discuss the production of sex cells by the 2 divisions that constitute meiosis in the reproductive organs. A. Meiosis - cell division that halves the genetic material, resulting in egg and sperm cells (gametes) 1) Meiosis I (1st meiotic division) - replication has already occurred creating 2 chromatids a. Prophase I - cross-over occurs i. cross-over - exchange of genetic material between homologous chromosomes during meiosis ii. homologous replicated chromosomes - the same but not identical, consisting of 2 chromatids held together by a centromere b. Metaphase I - chromosomes line up with respect to maternal and paternal origin c. Anaphase I - pairs separate d. Telophase I - original cell divides in 2 2) Meiosis II (2nd meiotic division) a. Prophase II - chromosomes condense and reappear, still replicated b. Metaphase II - replicated chromosomes attach to spindle fibers c. Anaphase II - chromatids move to opposite poles, now considered chromosomes d. Telophase II - each 2 cells resulting from meiosis I divide into 2 cells i. produce a total of 4 gametes Males - mature into 4 sperm cells 2. Describe the structural features of the scrotum and explain their functions. A. Scrotum - pouch of skin that encloses the testes 1) Dartos muscle - layer of smooth muscle fibers in the scrotal wall a. contraction brings the testes closer to the abdominal wall and causes a wrinkled appearance b. regulates the internal temperature of the testis at approximately 5 degrees below normal body temperature 2) Medial septum - divides the scrotum into 2 chambers B. Testes (sing. testis) - primary male reproductive organ; sperm cell-producing organ 1) Tunica albuginea - tough, white, fibrous capsule encloses each testis 2) Mediastinum testis - thickened extension of the tunica albuginea along the posterior border extend into the organ forming a mass 3) Septa - thin extensions of the mediastinal testis that pass into the testis and subdivide it into 250 lobules 4) Lobules - partitioned areas of the testis that house the seminiferous tubules and the interstitial cells a. Seminiferous tubules - coiled tubules in the lobules of each testis that function in sperm production i. germinal epithelium at periphery contains spermatogenic cells (immature sperm) and sustentacular cells (Sertoli’s cells) that support and nourish the immature sperm cells
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Chapter 22 b. Interstitial cells – tissue in the lobule of the testis that functions in the production of male sex hormones c. Rete testis – seminiferous tubules course posteriorly and unite to form a complex network of channels d. Efferent Ductules (Vasa Efferentia or Efferent ducts) - carry sperm from the rete testis of the testis to the epididymis e. Epididymis – tightly coiled thread-like tubule that leads from the efferent ducts of the testis to the ductus deferens i. emerges from the superior aspect of the testis that store sperm ii.
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This note was uploaded on 01/14/2011 for the course BIO 142 taught by Professor Unknown during the Spring '10 term at Northern Virginia Community College.

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Chapter 22 - Chapter 22 1 Discuss the production of sex...

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